Rubber Vulcanization Processes Employing An Eutectic Mixture

ABSTRACT

A process for preparing a rubber vulcanizate, the process comprising (i) providing a vulcanizable composition of matter including a sulfur-based curative, zinc oxide, and a eutectic solvent; and (ii) heating the vulcanizable composition to thereby effect vulcanization.

FIELD OF THE INVENTION

Embodiments of the present invention are directed toward processes forsulfur curing diene-based rubber compositions in the presence of zincoxide and a eutectic solvent.

BACKGROUND OF THE INVENTION

Zinc oxide, typically in combination with stearic acid, is commonly usedin the sulfur vulcanization of rubber. It is believed that zinc speciesand/or zinc oxide serve as an activator for the sulfur crosslinking. Itis also believed that the zinc oxide and stearic acid form, in situ,zinc species, and in combination with the zinc oxide, the rate andquality of the sulfur vulcanization process is impacted.

The zinc oxide conventionally employed in sulfur vulcanization processesis characterized by a BET surface area of less than 10 m²/g, which zincoxide can be referred to as micro zinc oxide. Generally, rubbervulcanization, especially in the tire art, requires at least about 2parts by weight (pbw) zinc oxide per 100 pbw rubber to effect a desiredcure. Nano zinc oxide, which has a BET surface area greater than 10m²/g, has also been proposed, and it has been suggested that the use ofnano zinc oxide can provide improved processes that ultimately requireless loading of zinc oxide or other zinc species. The use of nano zincoxide, however, presents several difficulties including manufacturingproblems as well as particle agglomeration.

There remains a desire to reduce the level of zinc, particularly zincoxide, used in the manufacture of tire components.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a process forpreparing a rubber vulcanizate, the process comprising providing avulcanizable composition of matter including a sulfur-based curative,zinc oxide, and a eutectic composition; and heating the vulcanizablecomposition to thereby effect vulcanization.

Yet other embodiments of the present invention provide a rubbervulcanizate comprising a vulcanized rubber network including a metalcompound dispersed throughout the rubber network, said vulcanized rubberincluding less than 2 parts by weight zinc oxide per 100 parts by weightrubber.

Still other embodiments of the present invention provide a rubbervulcanizate prepared by a process comprising the steps of preparing arubber vulcanizate, the process comprising providing a vulcanizablecomposition of matter including a sulfur-based curative, zinc oxide, anda eutectic composition; and heating the vulcanizable composition tothereby effect vulcanization.

Yet other embodiments of the present invention provide a method forpreparing a vulcanizable composition of matter, the method comprisingcombining a vulcanizable rubber, a curative, and a eutectic composition.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the invention are based, at least in part, on thediscovery of a process for the sulfur vulcanization of rubbercompositions that includes curing the rubber in the presence of a metalcompound (such as zinc species) and a eutectic composition. It hasunexpectedly been discovered that by including the eutectic compositionin the vulcanizable composition, the total loading of metal compoundsthat are necessary to achieve a desired cure can be appreciably reducedwithout a deleterious impact on cure rate and/or cure quality of therubber. And, in certain embodiments, the inclusion of the eutecticcomposition surprisingly has led to other improvements in one or more ofthe vulcanizate properties such as reduced wear and reduced rollingresistance. Accordingly, embodiments of the invention provide cured tirecomponents having relatively low levels of metal, such as zinc, andtechnologically useful level of cure.

Vulcanizable Compositions

As indicated above, a eutectic composition is introduced to avulcanizable composition for the production of a sulfur-curedvulcanizate. In addition to the eutectic composition, the vulcanizablecompositions of one or more embodiments include a vulcanizable rubber, afiller, a sulfur-based curative, stearic acid, and a metal compound,such as zinc oxide or derivatives zinc oxide. Other optional ingredientsmay also be included such as, but not limited to, processing and/orextender oils, resins, waxes, cure accelerators, scorch inhibitors,antidegradants, antioxidants, and other rubber compounding additivesknown in the art.

Eutectic Mixture

In one or more embodiments, a eutectic composition includes thosecompositions formed by combining two or more compounds that provide aresultant combination having a melting point lower than the respectivecompounds that are combined. For purposes of this specification,eutectic composition may be referred to as a eutectic mixture, eutecticcomplex, or eutectic pair. Each of the compounds that are combined maybe referred to, respectively, as a eutectic ingredient, eutecticconstituent, eutectic member, or compound for forming a eutecticcomposition (e.g. first and second compound). Depending on the relativeamounts of the respective eutectic ingredients, as well as thetemperature at which the observation is made, the eutectic compositionmay be in the form of a liquid, which may be referred to as a eutecticliquid or eutectic solvent. For a given composition, where relativeamounts of the respective ingredients are at or proximate to the lowestmelting point of the eutectic mixture, then composition may be referredto as a deep eutectic solvent, which may be referred to as DES.

Without wishing to be bound by any particular theory, it is believedthat the eutectic ingredients combine, otherwise react or interact toform a complex. Thus, any reference to eutectic mixture, or eutecticcombination, eutectic pair, or eutectic complex will includecombinations and reaction products or complexes between the constituentsthat are combined that yield a lower melting point than the respectiveconstituents. For example, in one or more embodiments, useful eutecticcompositions can be defined by the formula I:

Cat⁺X⁻zY

where Cat⁺ is a cation, X⁻ is a counter anion (e.g. Lewis Base), and zrefers to the number of Y molecules that interact with the counter anion(e.g. Lewis or Bronsted Acid). For example, Cat⁺ can include anammonium, phosphonium, or sulfonium cation. X⁻ may include, for example,a halide ion. Y may include, for example, a hydrogen bond donor, a metalhalide or a metal halide hydrate. In one or more embodiments, z is anumber that achieves a deep eutectic solvent, or in other embodiments anumber that otherwise achieves a complex having a melting point lowerthan the respective eutectic constituents.

In one or more embodiments, useful eutectic compositions include acombination of an acid and a base, where the acid and base may includeLewis acids and bases or Bronsted acids and bases. In one or moreembodiments, useful eutectic compositions include a combination of aquaternary ammonium salt with a metal halide (which are referred to asType I eutectic composition), a combination of a quaternary ammoniumsalt and a metal halide hydrate (which are referred to as Type IIeutectic composition), a combination of a quaternary ammonium salt and ahydrogen bond donor (which are referred to as Type III eutecticcomposition), or a combination of a metal halide hydrate and a hydrogenbond donor (which are referred to as Type IV eutectic composition).Analogous combinations of sulfonium or phosphonium in lieu of ammoniumcompounds can also be employed and can be readily envisaged by thosehaving skill in the art.

Quaternary Ammonium Salt

In one or more embodiments, the quaternary ammonium salt is a solid at20° C. In these or other embodiments, the metal halide and hydrogen bonddonor are solid at 20° C.

In one or more embodiments, useful quaternary ammonium salts, which mayalso be referred to as ammonium compounds, may be defined by the formulaII:

(R₁)(R₂)(R₃)(R₄)—N⁺-ϕ⁻

where each R₁, R₂, R₃, and R₄ is individually hydrogen or a monovalentorganic group, or, in the alternative, two of R₁, R₂, R₃, and R₄ join toform a divalent organic group, and t is a counter anion. In one or moreembodiments, at least one, in other embodiments at least two, and inother embodiments at least three of R₁, R₂, R₃, and R₄ are not hydrogen.

In one or more embodiments, the counter anion (e.g. ϕ⁻) is selected fromthe group consisting of halide (X⁻), nitrate (NO₃ ⁻), tetrafluoroborate(BF₄ ⁻), perchlorate (ClO₄ ⁻), triflate (SO₃CF₃ ⁻), trifluoroacetate(COOCF₃ ⁻). In one or more embodiments, ϕ⁻ is a halide ion, and incertain embodiments a chloride ion.

In one or more embodiments, the monovalent organic groups includehydrocarbyl groups, and the divalent organic groups includehydrocarbylene groups. In one or more embodiments, the monovalent anddivalent organic groups include a heteroatom, such as, but not limitedto, oxygen and nitrogen, and/or a halogen atom. Accordingly, themonovalent organic groups may include alkoxy groups, siloxy groups,ether groups, and ester groups, as well as carbonyl or acetylsubstituents. In one or more embodiments, the hydrocarbyl groups andhydrocarbylene group include from 1 (or the appropriate minimum number)to about 18 carbon atoms, in other embodiments from 1 to about 12 carbonatoms, and in other embodiments from 1 to about 6 carbon atoms. Thehydrocarbyl and hydrocarbylene groups may be branched, cyclic, orlinear. Exemplary types of hydrocarbyl groups include alkyl, cycloalkyl,aryl and alkylaryl groups. Exemplary types of hydrocarbylene groupsinclude alkylene, cycloalkylene, arylene, and alkylarylene groups. Inparticular embodiments, the hydrocarbyl groups are selected from thegroup consisting of methyl, ethyl, octadecyl, phenyl, and benzyl groups.In certain embodiments, the hydrocarbyl groups are methyl groups, andthe hydrocarbylene groups are ethylene or propylene group.

Useful types of ammonium compounds include secondary ammonium compounds,tertiary ammonium compounds, and quaternary ammonium compounds. In theseor other embodiments, the ammonium compounds include ammonium halidessuch as, but not limited to, ammonium chloride. In particularembodiments, the ammonium compound is a quaternary ammonium chloride. Incertain embodiments, R₁, R₂, R₃, and R₄ are hydrogen, and the ammoniumcompound is ammonium chloride. In one or more embodiments, the ammoniumcompounds are asymmetric.

In one or more embodiments, the ammonium compound includes an alkoxygroup and can be defined by the formula III:

(R₁)(R₂)(R₃)—N⁺—(R₄—OH)ϕ⁻

where each R₁, R₂, and R₃ is individually hydrogen or a monovalentorganic group, or, in the alternative, two of R₁, R₂, and R₃ join toform a divalent organic group, R₄ is a divalent organic group, and ϕ⁻ isa counter anion. In one or more embodiments, at least one, in otherembodiments at least two, and in other embodiments at least three of R₁,R₂, R₃, and are not hydrogen.

Examples of ammonium compounds defined by the formula III include, butare not limited to, N-ethyl-2-hydroxy-N,N-dimethylethanaminium chloride,2-hydroxy-N,N,N-trimethylethanaminium chloride (which is also known ascholine chloride), and N-benzyl-2-hydroxy-N,N-dimethlethanaminiumchloride.

In one or more embodiments, the ammonium compound includes ahalogen-containing substituent and can be defined by the formula IV:

ϕ⁻-(R₁)(R₂)(R₃)—N⁺—R₄X

where each R₁, R₂, and R₃ is individually hydrogen or a monovalentorganic group, or, in the alternative, two of R₁, R₂, and R₃ join toform a divalent organic group, R₄ is a divalent organic group, X is ahalogen atom, and ϕ⁻ is a counter anion. In one or more embodiments, atleast one, in other embodiments at least two, and in other embodimentsat least three of R₁, R₂, R₃, and are not hydrogen. In one or moreembodiments, X is chlorine.

Examples of ammonium compounds defined by the formula III include, butare not limited to, 2-chloro-N,N,N-trimethylethanaminium (which is alsoreferred to as chlorcholine chloride), and2-(chlorocarbonyloxy)-N,N,N-trimethylethanaminium chloride.

Hydrogen-Bond Donor Compounds

In one or more embodiments, the hydrogen-bond donor compounds, which mayalso be referred to as HBD compounds, include, but are not limited to,amines, amides, carboxylic acids, and alcohols. In one or moreembodiments, the hydrogen-bond donor compound includes a hydrocarbonchain constituent. The hydrocarbon chain constituent may include acarbon chain length including at least 2, in other embodiments at least3, and in other embodiments at least 5 carbon atoms. In these or otherembodiments, the hydrocarbon chain constituent has a carbon chain lengthof less than 30, in other embodiments less than 20, and in otherembodiments less than 10 carbon atoms.

In one or more embodiments, useful amines include those compoundsdefined by the formula:

R₁—(CH₂)_(x)—R₂

wherein R₁ and R₂ are —NH₂, —NHR₃, or —NR₃R₄, and x is an integer of atleast 2. In one or more embodiments, x is from 2 to about 10, in otherembodiments from about 2 to about 8, and in other embodiments from about2 to about 6.

Specific examples of useful amines include, but are not limited to,aliphatic amines, ethylenediamine, diethylenetriamine,aminoethylpiperazine, triethylenetetramine, tris(2-aminoethyl)amine,N,N′-bis-(2aminoethyle)piperazine, piperazinoethylethylenediamine, andtetraethylenepentaamine, propyleneamine, aniline, substituted aniline,and combinations thereof.

In one or more embodiments, useful amides include those compoundsdefined by the formula:

R—CO—NH₂

wherein R is H, NH₂, CH₃, or CF₃.

Specific examples of useful amides include, but are not limited to,urea, 1-methyl urea, 1,1-dimethyl urea, 1,3-dimethylurea, thiourea,urea, benzamide, acetamide, and combinations thereof.

In one or more embodiments, useful carboxylic acids includemono-functional, di-functional, and tri-functional organic acids. Theseorganic acids may include alkyl acids, aryl acids, and mixed alkyl-arylacids.

Specific examples of useful mono-functional carboxylic acids include,but are not limited to, aliphatic acids, phenylpropionic acid,phenylacetic acid, benzoic acid, and combinations thereof. Specificexamples of di-functional carboxylic acids include, but are not limitedto, oxalic acid, malonic acid, adipic acid, succinic acid, andcombinations thereof. Specific examples of tri-functional carboxylicacids include citric acid, tricarballylic acid, and combinationsthereof.

Types of alcohols include, but are not limited to, monools, diols, andtriols. Specific examples of monools include aliphatic alcohols, phenol,substituted phenol, and mixtures thereof. Specific examples of diolsinclude ethylene glycol, propylene glycol, resorcinol, substitutedresorcinol, and mixtures thereof. Specific examples of triols include,but are not limited to, glycerol, benzene triol, and mixtures thereof.

Metal Halides

Types of metal halides include, but are not limited to, chlorides,bromides, iodides and fluorides. In one or more embodiments, these metalhalides include, but are not limited to, transition metal halides. Theskilled person can readily envisage the corresponding metal halidehydrates.

Specific examples of useful metal halides include, but are not limitedto, aluminum chloride, aluminum bromide, aluminum iodide, zinc chloride,zinc bromide, zinc iodide, tin chloride, tin bromide, tin iodide, ironchloride, iron bromide, iron iodide, and combinations thereof. Theskilled person can readily envisage the corresponding metal halidehydrates. For example, aluminum chloride hexahydrate and copper chloridedihydrate correspond to the halides mentioned above.

Formation of Eutectic Complex

The skilled person can select the appropriate eutectic members at theappropriate molar ratio to provide the desired eutectic composition. Theskilled person appreciates that the molar ratio of the first compound(e.g. Lewis base) of the pair to the second compound (e.g. Lewis acid)of the pair will vary based upon the compounds selected. As the skilledperson will also appreciate, the melting point suppression of a eutecticsolvent includes the eutectic point, which is the molar ratio of thefirst compound to the second compound that yields the minimum meltingpoint suppression (i.e. deep eutectic solvent). The molar ratio of thefirst compound to the second compound can, however, be varied tononetheless produce a suppression in the melting point of a eutecticsolvent relative to the individual melting points of the first andsecond compounds that is not the minimum melting point. Practice of oneor more embodiments of the present invention therefore includes theformation a eutectic solvent at molar ratios outside of the eutecticpoint.

In one or more embodiments, the compounds of the eutectic pair, as wellas the molar ratio of the first compound to the second compound of thepair, are selected to yield a mixture having a melting point below 130°C., in other embodiments below 110° C., in other embodiments below 100°C., in other embodiments below 80° C., in other embodiments below 60°C., in other embodiments below 40° C., and in other embodiments below30° C. In these or other embodiments, the compounds of the eutecticpair, as well as the molar ratio of the compounds, are selected to yielda mixture having a melting point above 0° C., in other embodiments above10° C., in other embodiments above 20° C., in other embodiments above30° C., and in other embodiments above 40° C.

In one or more embodiments, the compounds of the eutectic pair, as wellas the molar ratio of the first compound to the second compound of thepair, are selected to yield a eutectic solvent having an ability orcapacity to dissolve desired metal compounds, which may be referred toas solubility or solubility power. As the skilled person willappreciate, this solubility can be quantified based upon the weight ofmetal compound dissolved in a given weight of eutectic solvent over aspecified time at a specified temperature and pressure when saturatedsolutions are prepared. In one or more embodiments, the eutecticsolvents of the present invention are selected to achieve a solubilityfor zinc oxide, over 24 hours at 50° C. under atmospheric pressure, ofgreater than 100 ppm, in other embodiments greater than 500 ppm, inother embodiments greater than 1000 ppm, in other embodiments greaterthan 1200 ppm, in other embodiments greater than 1400 ppm, and in otherembodiments greater than 1600 ppm, where ppm is measured on a weightsolute to weight solvent basis.

In one or more embodiments, a eutectic solvent is formed by combiningthe first compound with the second compound at an appropriate molarratio to provide a solvent composition (i.e. liquid composition at thedesired temperature). The mixture may be mechanically agitated by usingvarious techniques including, but not limited to, solid state mixing orblending techniques. Generally speaking, the mixture is mixed orotherwise agitated until a liquid that is visibly homogeneous is formed.Also, the mixture may be formed at elevated temperatures. For example,the eutectic solvent may be formed by heating the mixture to atemperature of greater than 50° C., in other embodiments greater than70° C., and in other embodiments greater than 90° C. Mixing may continueduring the heating of the mixture. Once a desired mixture is formed, theeutectic solvent can be cooled to room temperature. In one or moreembodiments, the cooling of the eutectic solvent may take place at acontrolled rate such as at a rate of less than 1° C./min.

In one or more embodiments, useful eutectic compositions can be obtainedcommercially. For example, deep eutectic solvents are commerciallyavailable under the tradenames Ionic Liquids from Scionix. Usefuleutectic compositions are also generally known as described in U.S.Publ. Nos. 2004/0097755 A1 and 2011/0207633 A1, which are incorporatedherein by reference.

Vulcanizable Rubber

In one or more embodiments, the vulcanizable rubber, which may also bereferred to as a rubber or a vulcanizable elastomer, may include thosepolymers that can be vulcanized to form compositions possessing rubberyor elastomeric properties. These elastomers may include natural andsynthetic rubbers. The synthetic rubbers typically derive from thepolymerization of conjugated diene monomer, the copolymerization ofconjugated diene monomer with other monomer such as vinyl-substitutedaromatic monomer, or the copolymerization of ethylene with one or moreα-olefins and optionally one or more diene monomers.

Exemplary elastomers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched, andstar-shaped structures. These elastomers may also include one or morefunctional units, which typically include heteroatoms.

Filler

As suggested above, the vulcanizable compositions of the invention mayinclude one or more fillers. These filler materials may includereinforcing and non-reinforcing fillers. Exemplary fillers includecarbon black, silica, and sundry inorganic fillers.

Useful carbon blacks include furnace blacks, channel blacks, and lampblacks. More specific examples of carbon blacks include super abrasionfurnace blacks, intermediate super abrasion furnace blacks, highabrasion furnace blacks, fast extrusion furnace blacks, fine furnaceblacks, semi-reinforcing furnace blacks, medium processing channelblacks, hard processing channel blacks, conducting channel blacks, andacetylene blacks.

In particular embodiments, the carbon blacks may have a surface area(EMSA) of at least 20 m²/g and in other embodiments at least 35 m²/g;surface area values can be determined by ASTM D-1765 using thecetyltrimethylammonium bromide (CTAB) technique. The carbon blacks maybe in a pelletized form or an unpelletized flocculent form. Thepreferred form of carbon black may depend upon the type of mixingequipment used to mix the rubber compound.

Examples of suitable silica fillers include precipitated amorphoussilica, wet silica (hydrated silicic acid), dry silica (anhydroussilicic acid), fumed silica, calcium silicate, aluminum silicate,magnesium silicate, and the like.

In one or more embodiments, silicas may be characterized by theirsurface areas, which give a measure of their reinforcing character. TheBrunauer, Emmet and Teller (“BET”) method (described in J. Am. Chem.Soc., vol. 60, p. 309 et seq.) is a recognized method for determiningthe surface area. The BET surface area of silica is generally less than450 m²/g. Useful ranges of surface area include from about 32 to about400 m²/g, about 100 to about 250 m²/g, and about 150 to about 220 m²/g.

Where one or more silicas is employed, the pH's of the silicas aregenerally from about 5 to about 7 or slightly over 7, or in otherembodiments from about 5.5 to about 6.8.

In one or more embodiments, where silica is employed as a filler (aloneor in combination with other fillers), a coupling agent and/or ashielding agent may be added to the rubber compositions during mixing inorder to enhance the interaction of silica with the elastomers. Usefulcoupling agents and shielding agents are disclosed in U.S. Pat. Nos.3,842,111, 3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919,5,583,245, 5,663,396, 5,674,932, 5,684,171, 5,684,172 5,696,197,6,608,145, 6,667,362, 6,579,949, 6,590,017, 6,525,118, 6,342,552, and6,683,135, which are incorporated herein by reference. Examples ofsulfur-containing silica coupling agents includebis(trialkoxysilylorgano)polysulfides or mercapto-organoalkoxysilanes.Types of bis(trialkoxysilylorgano)polysulfides includebis(trialkoxysilylorgano)disulfide andbis(trialkoxysilylorgano)tetrasulfides.

Other useful filler materials include sundry inorganic and organicfillers. Examples of organic fillers include starch. Examples ofinorganic fillers include silica, aluminum hydroxide, magnesiumhydroxide, titanium oxides, boron nitrides, iron oxides, mica, talc(hydrated magnesium silicate), and clays (hydrated aluminum silicates).

Resins

As suggested above, the vulcanizable compositions of the invention mayinclude one or more resins. These resins may include phenolic resins andhydrocarbon resins such as cycloaliphatic resins, aliphatic resins,aromatic resins, terpene resins, and combinations thereof. Useful resinsare commercially available from various companies including, forexample, Chemfax, Dow Chemical Company, Eastman Chemical Company,Idemitsu, Neville Chemical Company, Nippon, Polysat Inc., ResinallCorp., Pinova Inc., Yasuhara Chemical Co., Ltd., Arizona Chemical, andSI Group Inc., and Zeon under various trade names.

In one or more embodiments, useful hydrocarbon resins may becharacterized by a glass transition temperature (Tg) of from about 30 toabout 160° C., in other embodiments from about 35 to about 60° C., andin other embodiments from about 70 to about 110° C. In one or moreembodiments, useful hydrocarbon resins may also be characterized by itssoftening point being higher than its Tg. In certain embodiments, usefulhydrocarbon resins have a softening point of of from about 70 to about160° C., in other embodiments from about 75 to about 120° C., and inother embodiments from about 120 to about 160° C.

In certain embodiments, one or more cycloaliphatic resins are used incombination with one or more of an aliphatic, aromatic, and terpeneresins. In one or more embodiments, one or more cycloaliphatic resinsare employed as the major weight component (e.g. greater than 50% byweight) relative to total load of resin. For example, the resinsemployed include at least 55% by weight, in other embodiments at least80% by weight, and in other embodiments at least 99% by weight of one ormore cycloaliphatic resins.

In one or more embodiments, cycloaliphatic resins include bothcycloaliphatic homopolymer resins and cycloaliphatic copolymer resinsincluding those deriving from cycloaliphatic monomers, optionally incombination with one or more other (non-cycloaliphatic) monomers, withthe majority by weight of all monomers being cycloaliphatic.Non-limiting examples of useful cycloaliphatic resins suitable includecyclopentadiene (“CPD”) homopolymer or copolymer resins,dicyclopentadiene (“DCPD”) homopolymer or copolymer resins, andcombinations thereof. Non-limiting examples of cycloaliphatic copolymerresins include CPD/vinyl aromatic copolymer resins, DCPD/vinyl aromaticcopolymer resins, CPD/terpene copolymer resins, DCPD/terpene copolymerresins, CPD/aliphatic copolymer resins (e.g., CPD/C5 fraction copolymerresins), DCPD/aliphatic copolymer resins (e.g., DCPD/C5 fractioncopolymer resins), CPD/aromatic copolymer resins (e.g., CPD/C9 fractioncopolymer resins), DCPD/aromatic copolymer resins (e.g., DCPD/C9fraction copolymer resins), CPD/aromatic-aliphatic copolymer resins(e.g., CPD/C5 & C9 fraction copolymer resins), DCPD/aromatic-aliphaticcopolymer resins (e.g., DCPD/C5 & C9 fraction copolymer resins),CPD/vinyl aromatic copolymer resins (e.g., CPD/styrene copolymerresins), DCPD/vinyl aromatic copolymer resins (e.g., DCPD/styrenecopolymer resins), CPD/terpene copolymer resins (e.g., limonene/CPDcopolymer resin), and DCPD/terpene copolymer resins (e.g., limonene/DCPDcopolymer resins). In certain embodiments, the cycloaliphatic resin mayinclude a hydrogenated form of one of the cycloaliphatic resinsdiscussed above (i.e., a hydrogenated cycloaliphatic resin). In otherembodiments, the cycloaliphatic resin excludes any hydrogenatedcycloaliphatic resin; in other words, the cycloaliphatic resin is nothydrogenated.

In certain embodiments, one or more aromatic resins are used incombination with one or more of an aliphatic, cycloaliphatic, andterpene resins. In one or more embodiments, one or more aromatic resinsare employed as the major weight component (e.g. greater than 50% byweight) relative to total load of resin. For example, the resinsemployed include at least 55% by weight, in other embodiments at least80% by weight, and in other embodiments at least 99% by weight of one ormore aromatic resins.

In one or more embodiments, aromatic resins include both aromatichomopolymer resins and aromatic copolymer resins including thosederiving from one or more aromatic monomers in combination with one ormore other (non-aromatic) monomers, with the largest amount of any typeof monomer being aromatic. Non-limiting examples of useful aromaticresins include coumarone-indene resins and alkyl-phenol resins, as wellas vinyl aromatic homopolymer or copolymer resins, such as thosederiving from one or more of the following monomers:alpha-methylstyrene, styrene, ortho-methylstyrene, meta-methylstyrene,para-methylstyrene, vinyltoluene, para(tert-butyl)styrene,methoxystyrene, chlorostyrene, hydroxystyrene, vinylmesitylene,divinylbenzene, vinylnaphthalene or any vinyl aromatic monomer resultingfrom C9 fraction or C8-C10 fraction. Non-limiting examples ofvinylaromatic copolymer resins include vinylaromatic/terpene copolymerresins (e.g., limonene/styrene copolymer resins), vinylaromatic/C5fraction resins (e.g., C5 fraction/styrene copolymer resin),vinylaromatic/aliphatic copolymer resins (e.g., CPD/styrene copolymerresin, and DCPD/styrene copolymer resin). Non-limiting examples ofalkyl-phenol resins include alkylphenol-acetylene resins such asp-tert-butylphenol-acetylene resins, alkylphenol-formaldehyde resins(such as those having a low degree of polymerization. In certainembodiments, the aromatic resin may include a hydrogenated form of oneof the aromatic resins discussed above (i.e., a hydrogenated aromaticresin). In other embodiments, the aromatic resin excludes anyhydrogenated aromatic resin; in other words, the aromatic resin is nothydrogenated.

In certain embodiments, one or more aliphatic resins are used incombination with one or more of cycloaliphatic, aromatic and terpeneresins. In one or more embodiments, one or more aliphatic resins areemployed as the major weight component (e.g. greater than 50% by weight)relative to total load of resin. For example, the resins employedinclude at least 55% by weight, in other embodiments at least 80% byweight, and in other embodiments at least 99% by weight of one or morealiphatic resins.

In one or more embodiments, aliphatic resins include both aliphatichomopolymer resins and aliphatic copolymer resins including thosederiving from one or more aliphatic monomers in combination with one ormore other (non-aliphatic) monomers, with the largest amount of any typeof monomer being aliphatic. Non-limiting examples of useful aliphaticresins include C5 fraction homopolymer or copolymer resins, C5fraction/C9 fraction copolymer resins, C5 fraction/vinyl aromaticcopolymer resins (e.g., C5 fraction/styrene copolymer resin), C5fraction/cycloaliphatic copolymer resins, C5 fraction/C9fraction/cycloaliphatic copolymer resins, and combinations thereof.Non-limiting examples of cycloaliphatic monomers include, but are notlimited to cyclopentadiene (“CPD”) and dicyclopentadiene (“DCPD”). Incertain embodiments, the aliphatic resin may include a hydrogenated formof one of the aliphatic resins discussed above (i.e., a hydrogenatedaliphatic resin). In other embodiments, the aliphatic resin excludes anyhydrogenated aliphatic resin; in other words, in such embodiments, thealiphatic resin is not hydrogenated.

In one or more embodiments, terpene resins include both terpenehomopolymer resins and terpene copolymer resins including those derivingfrom one or more terpene monomers in combination with one or more other(non-terpene) monomers, with the largest amount of any type of monomerbeing terpene. Non-limiting examples of useful terpene resins includealpha-pinene resins, beta-pinene resins, limonene resins (e.g.,L-limonene, D-limonene, dipentene which is a racemic mixture of L- andD-isomers), beta-phellandrene, delta-3-carene, delta-2-carene,pinene-limonene copolymer resins, terpene-phenol resins, aromaticmodified terpene resins and combinations thereof. In certainembodiments, the terpene resin may include a hydrogenated form of one ofthe terpene resins discussed above (i.e., a hydrogenated terpene resin).In other embodiments, the terpene resin excludes any hydrogenatedterpene resin; in other words, in such embodiments, the terpene resin isnot hydrogenated.

Curatives

The rubber curing agents (also called vulcanizing agents) includesulfur-based curing systems. Curing agents are described in Kirk-Othmer,ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Vol. 20, pgs. 365-468, (3^(rd) Ed.1982), particularly Vulcanization Agents and Auxiliary Materials, pgs.390-402, and A. Y. Coran, Vulcanization, ENCYCLOPEDIA OF POLYMER SCIENCEAND ENGINEERING, (2^(nd) Ed. 1989), which are incorporated herein byreference. In one or more embodiments, the curative is sulfur. Examplesof suitable sulfur vulcanizing agents include “rubbermaker's” solublesulfur; sulfur donating vulcanizing agents, such as an amine disulfide,polymeric polysulfide or sulfur olefin adducts; and insoluble polymericsulfur. Vulcanizing agents may be used alone or in combination. Theskilled person will be able to readily select the amount of vulcanizingagents to achieve the level of desired cure.

In one or more embodiments, the curative is employed in combination witha cure accelerator. In one or more embodiments, accelerators are used tocontrol the time and/or temperature required for vulcanization and toimprove properties of the vulcanizate. Examples of accelerators includethiazole vulcanization accelerators, such as 2-mercaptobenzothiazole,dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl-sulfenamide (CBS),and the like, and guanidine vulcanization accelerators, such asdiphenylguanidine (DPG) and the like. The skilled person will be able toreadily select the amount of cure accelerators to achieve the level ofdesired cure.

Other Ingredients

Other ingredients that are typically employed in rubber compounding mayalso be added to the rubber compositions. These include accelerators,accelerator activators, oils, additional plasticizers, waxes, scorchinhibiting agents, processing aids, zinc oxide, tackifying resins,reinforcing resins, fatty acids such as stearic acid, peptizers, andantidegradants such as antioxidants and antiozonants. In particularembodiments, the oils that are employed include those conventionallyused as extender oils. Useful oils or extenders that may be employedinclude, but are not limited to, aromatic oils, paraffinic oils,naphthenic oils, vegetable oils other than castor oils, low PCA oilsincluding MES, TDAE, and SRAE, and heavy naphthenic oils. Suitable lowPCA oils also include various plant-sourced oils such as can beharvested from vegetables, nuts, and seeds. Non-limiting examplesinclude, but are not limited to, soy or soybean oil, sunflower oil,safflower oil, corn oil, linseed oil, cotton seed oil, rapeseed oil,hemp oil, cashew oil, sesame oil, camellia oil, jojoba oil, macadamianut oil, coconut oil, and palm oil.

Metal Activator and Organic Acid

As suggested above, the vulcanizable compositions of the presentinvention include a metal compound. In one or more embodiments, themetal compound is an activator (i.e. assists in the vulcanization orcure of the rubber). In other embodiments, the metal activator is ametal oxide. In particular embodiments, the metal activator is zincoxide. In other embodiments, the metal activator is a zinc species thatis formed in situ through a reaction or interaction between zinc oxideand organic acid (e.g. stearic acid). In other embodiments, the metalcompound is a magnesium compound such as magnesium hydroxide. In otherembodiments, the metal compound is an iron compound such as an ironoxide. In other embodiments, the metal compound is a cobalt compoundsuch as a cobalt carboxylate.

In one or more embodiments, the zinc oxide is an unfunctionalized zincoxide characterized by a BET surface area of less than 10 m²/g, in otherembodiments less than 9 m²/g, and in other embodiments less than 8 m²/g.In other embodiments, nano zinc oxide is employed, which includes thosezinc oxide particles that are characterized by a BET surface area ofgreater than 10 m²/g.

In one or more embodiments, the organic acid is a carboxylic acid. Inparticular embodiments, the carboxylic acid is a fatty acid includingsaturated and unsaturated fatty acids. In particular embodiments,saturated fatty acids, such as stearic acid, are employed. Other usefulacids include, but are not limited to, palmitic acid, arachidic acid,oleic acid, linoleic acid, and arachidonic acid.

Ingredient Amounts Rubber

In one or more embodiments, the vulcanizable compositions include atleast 20, in other embodiments at least 30, and in other embodiments atleast 40 percent by weight of the rubber component, based upon theentire weight of the composition. In these or other embodiments, thevulcanizable compositions include at most 90, in other embodiments atmost 70, and in other embodiments at most 60 percent by weight of therubber component based on the entire weight of the composition. In oneor more embodiments, the vulcanizable compositions include from about 20to about 90, in other embodiments from about 30 to about 70, and inother embodiments from about 40 to about 60 percent by weight of therubber component based upon the entire weight of the composition.

Eutectic Composition

In one or more embodiments, the vulcanizable compositions includegreater than 0.005, in other embodiments greater than 0.01, and in otherembodiments greater than 0.02 parts by weight (pbw) of the eutecticcomposition per 100 parts by weight rubber (phr). In these or otherembodiments, the vulcanizable compositions include less than 3, in otherembodiments less than 1, and in other embodiments less than 0.1 pbw ofthe eutectic composition phr. In one or more embodiments, thevulcanizable compositions include from about 0.005 to about 3, in otherembodiments from about 0.01 to about 1, and in other embodiments fromabout 0.02 to about 0.1 pbw of the eutectic composition phr.

In one or more embodiments, the amount of eutectic solvent can bedescribed with reference to the loading of metal activator (such as zincoxide). In one or more embodiments, the vulcanizable compositionsinclude greater than 2, in other embodiments greater than 3, and inother embodiments greater than 5 wt % eutectic solvent based upon thetotal weight of the eutectic solvent and the metal activator (e.g. zincoxide) present within the vulcanizable composition. In these or otherembodiments, the vulcanizable compositions include less than 15, inother embodiments less than 12, and in other embodiments less than 10 wt% eutectic solvent based upon the total weight of the eutectic solventand the metal activator (e.g. zinc oxide) present within thevulcanizable composition. In one or more embodiments, the vulcanizablecompositions include from about 2 to about 15, in other embodiments fromabout 3 to about 12, and in other embodiments from about 5 to about 10wt % eutectic solvent based upon the total weight of the eutecticsolvent and the metal activator (e.g. zinc oxide) present within thevulcanizable composition.

Metal Compound

In one or more embodiments, the vulcanizable compositions includegreater than 0.05, in other embodiments greater than 0.1, and in otherembodiments greater than 0.15 parts by weight (pbw) of metal activator(e.g. zinc oxide) per 100 parts by weight rubber (phr). In these orother embodiments, the vulcanizable composition includes less than 2, inother embodiments less than 1, and in other embodiments less than 0.75pbw of metal activator (e.g. zinc oxide) phr. In one or moreembodiments, the vulcanizable composition includes from about 0.05 toabout 2, in other embodiments from about 0.1 to about 1, and in otherembodiments from about 0.15 to about 0.75 pbw of metal activator (e.g.zinc oxide) phr.

Organic Acid

In one or more embodiments, the vulcanizable compositions includegreater than 0.5, in other embodiments greater than 0.7, and in otherembodiments greater than 1.0 parts by weight (pbw) of organic acid (e.g.stearic acid) per 100 parts by weight rubber (phr). In these or otherembodiments, the vulcanizable composition includes less than 5, in otherembodiments less than 3, and in other embodiments less than 2 pbw oforganic acid (e.g. stearic acid) phr. In one or more embodiments, thevulcanizable composition includes from about 0.5 to about 5, in otherembodiments from about 0.7 to about 3, and in other embodiments fromabout 1.0 to about 2 pbw of organic acid (e.g. stearic acid) phr.

Filler

In one or more embodiments, the vulcanizable compositions include atleast 0, in other embodiments at least 10, and in other embodiments atleast 20 parts by weight (pbw) of filler per 100 parts by weight rubber(phr). In these or other embodiments, the vulcanizable compositionincludes at most 200, in other embodiments at most 100, and in otherembodiments at most 70 pbw of filler phr. In one or more embodiments,the vulcanizable composition includes from about 0 to about 200, inother embodiments from about 10 to about 100, and in other embodimentsfrom about 20 to about 70 pbw of filler phr.

Carbon Black

In one or more embodiments, the vulcanizable compositions include atleast 0, in other embodiments at least 10, and in other embodiments atleast 20 parts by weight (pbw) of a carbon black per 100 parts by weightrubber (phr). In these or other embodiments, the vulcanizablecomposition includes at most 200, in other embodiments at most 100, andin other embodiments at most 70 pbw of a carbon black phr. In one ormore embodiments, the vulcanizable composition includes from about 0 toabout 200, in other embodiments from about 10 to about 100, and in otherembodiments from about 20 to about 70 pbw of a carbon black phr.

Silica

In one or more embodiments, the vulcanizable compositions include atleast 5, in other embodiments at least 25, in other embodiments at least50, and in other embodiments at least 70 parts by weight (pbw) silicaper 100 parts by weight rubber (phr). In these or other embodiments, thevulcanizable composition includes at most 200, in other embodiments atmost 130, and in other embodiments at most 80 pbw of the silica phr. Inone or more embodiments, the vulcanizable composition includes fromabout 5 to about 200, in other embodiments from about 25 to about 130,and in other embodiments from about 50 to about 80 pbw of silica phr.

Filler Ratio

In one or more embodiments, the vulcanizable compositions can becharacterized by the ratio of the amount of a first filler to the amountof a second filler. In one or more embodiments, the ratio of the amountof carbon black to silica is about 1:1, in other embodiments about 10:1,in other embodiments about 14:1, and in other embodiments about 20:1. Inone or more embodiments, the ratio of the amount of carbon black tosilica is about 1:5, in other embodiments about 1:10, in otherembodiments about 1:14, and in other embodiments about 1:20.

Silica Coupling Agent

In one or more embodiments, the vulcanizable compositions include atleast 1, in other embodiments at least 2, and in other embodiments atleast 5 parts by weight (pbw) silica coupling agent per 100 parts byweight silica. In these or other embodiments, the vulcanizablecomposition includes at most 20, in other embodiments at most 15, and inother embodiments at most 10 pbw of the silica coupling agent per 100parts by weight silica. In one or more embodiments, the vulcanizablecomposition includes from about 1 to about 20, in other embodiments fromabout 2 to about 15, and in other embodiments from about 5 to about 10pbw of silica coupling agent per 100 parts by weight silica.

Resin

In one or more embodiments, the vulcanizable compositions includegreater than 1, in other embodiments greater than 15, in otherembodiments greater than 25, and in other embodiments greater than 35parts by weight (pbw) of resin (e.g. hydrocarbon resin) per 100 parts byweight rubber (phr). In these or other embodiments, the vulcanizablecomposition includes less than 150, in other embodiments less than 120,and in other embodiments less than 90 pbw of resin (e.g. hydrocarbonresin) phr. In one or more embodiments, the vulcanizable compositionincludes from about 1 to about 150, in other embodiments from about 15to about 120, and in other embodiments from about 25 to about 90 pbw ofresin (e.g. hydrocarbon resin) phr.

Process Overview

In one or more embodiments, vulcanizable compositions are prepared bymixing a vulcanizable rubber and the eutectic solvent to form amasterbatch, and then subsequently adding a curative to the masterbatch.The preparation of the masterbatch may take place using one or moresub-mixing steps where, for example, one or more ingredients may beadded to the composition sequentially after an initial mixture isprepared by mixing two or more ingredients. Also, using conventionaltechnology, additional ingredients can be added in the preparation ofthe vulcanizable compositions such as, but not limited to, carbon black,additional fillers, chemically-treated inorganic oxide, silica, silicacoupling agent, silica dispersing agent, processing oils, processingaids such as zinc oxide and fatty acid, and antidegradants such asantioxidants or antiozonants.

In one or more embodiments, the eutectic composition is prepared priorto introducing the eutectic composition to the vulcanizable rubber. Inother words, the first constituent of the mixture is pre-combined withthe second constituent of the mixture prior to introducing the mixtureto the vulcanizable composition. In one or more embodiments, thecombined constituents of the mixture are mixed until a homogeneousliquid composition is observed.

In one or more embodiments, the eutectic composition is pre-combinedwith one or more ingredients of the rubber formulation prior tointroducing the eutectic mixture to the vulcanizable composition. Inother words, in one or more embodiments, a constituent of thevulcanizable composition (e.g. a metal compound such as zinc oxide) iscombined with the eutectic mixture to form a pre-combination ormasterbatch prior to introducing the pre-combination to the mixer inwhich the rubber is mixed. For example, zinc oxide may be dissolved inthe eutectic solvent prior to introduction to the rubber within themixer. In other embodiments, the eutectic composition is the minorcomponent of the pre-combination, and therefore the constituent that ispre-mixed with the eutectic composition acts as a carrier for theeutectic composition. For example, the eutectic composition can becombined with a larger volume of zinc oxide, and the zinc oxide will actas a carrier for delivery the combination of zinc oxide and eutecticcomposition as a solid to the rubber within the mixer. In yet otherembodiments, one of the members of the eutectic pair acts as a solidcarrier for the eutectic composition, and therefore the combination ofthe first and second ingredients of the eutectic composition form apre-combination that can be added as a solid to the rubber within themixer. The skilled person will appreciate that mixtures of this naturecan be formed by combining an excess of the first or second eutecticmembers is excess, relative to the other eutectic member, to maintain asolid composition at the desired temperature.

In one or more embodiments, the eutectic solvent is introduced to thevulcanizable rubber as an initial ingredient in the formation of arubber masterbatch. As a result, the eutectic solvent undergoes highshear, high temperature mixing with the rubber. In one or moreembodiments, the eutectic solvent undergoes mixing with the rubber atminimum temperatures in excess of 110° C., in other embodiments inexcess of 130° C., and in other embodiments in excess of 150° C. In oneor more embodiments, high shear, high temperature mixing takes place ata temperature from about 110° C. to about 170° C.

In other embodiments, the eutectic solvent is introduced to thevulcanizable rubber, either sequentially or simultaneously, with thesulfur-based curative. As a result, the eutectic solvent undergoesmixing with the vulcanizable rubber at a maximum temperature below 110°C., in other embodiments below 105° C., and in other embodiments below100° C. In one or more embodiments, mixing with the curative takes placeat a temperature from about 70° C. to about 110° C.

As with the eutectic solvent, the zinc oxide and the stearic acid can beadded as initial ingredients to the rubber masterbatch, and thereforethese ingredients will undergo high temperature, high shear mixing.Alternatively, the zinc oxide and the stearic acid can be added alongwith the sulfur-based curative and thereby only undergo low-temperaturemixing.

In one or more embodiments, the zinc oxide is introduced to thevulcanizable rubber separately and individually from the eutecticsolvent. In other embodiments, the zinc oxide and the eutectic solventare pre-combined to form a zinc oxide masterbatch, which may include asolution in which the zinc oxide is dissolved or otherwise dispersed inthe eutectic solvent. The zinc oxide masterbatch can then be introducedto the vulcanizable rubber.

Mixing Conditions

In one or more embodiments, a vulcanizable composition is prepared byfirst mixing a vulcanizable rubber and the eutectic solvent at atemperature of from about 140 to about 180, or in other embodiments fromabout 150 to about 170° C. In certain embodiments, following the initialmixing, the composition (i.e., masterbatch) is cooled to a temperatureof less than 100° C., or in other embodiments less than 80° C., and acurative is added. In certain embodiments, mixing is continued at atemperature of from about 90 to about 110° C., or in other embodimentsfrom about 95 to about 105° C., to prepare the final vulcanizablecomposition.

In one or more embodiments, the masterbatch mixing step, or one or moresub-steps of the masterbatch mixing step, may be characterized by thepeak temperature obtained by the composition during the mixing. Thispeak temperature may also be referred to as a drop temperature. In oneor more embodiments, the peak temperature of the composition during themasterbatch mixing step may be at least 140° C., in other embodiments atleast 150° C., and in other embodiments at least 160° C. In these orother embodiments, the peak temperature of the composition during themasterbatch mixing step may be from about 140 to about 200° C., in otherembodiments from about 150 to about 190° C., and in other embodimentsfrom about 160 to about 180° C.

Final Mixing Step

Following the masterbatch mixing step, a curative or curative system isintroduced to the composition and mixing is continued to ultimately formthe vulcanizable composition of matter. This mixing step may be referredto as the final mixing step, the curative mixing step, or the productivemixing step. The resultant product from this mixing step may be referredto as the vulcanizable composition.

In one or more embodiments, the final mixing step may be characterizedby the peak temperature obtained by the composition during final mixing.As the skilled person will recognize, this temperature may also bereferred to as the final drop temperature. In one or more embodiments,the peak temperature of the composition during final mixing may be atmost 130° C., in other embodiments at most 110° C., and in otherembodiments at most 100° C. In these or other embodiments, the peaktemperature of the composition during final mixing may be from about 80to about 130° C., in other embodiments from about 90 to about 115° C.,and in other embodiments from about 95 to about 105° C.

Mixing Equipment

All ingredients of the vulcanizable compositions can be mixed withstandard mixing equipment such as internal mixers (e.g. Banbury orBrabender mixers), extruders, kneaders, and two-rolled mills. Mixing cantake place singularly or in tandem. As suggested above, the ingredientscan be mixed in a single stage, or in other embodiments in two or morestages. For example, in a first stage (i.e., mixing stage), whichtypically includes the rubber component and filler, a masterbatch isprepared. Once the masterbatch is prepared, the vulcanizing agents maybe introduced and mixed into the masterbatch in a final mixing stage,which is typically conducted at relatively low temperatures so as toreduce the chances of premature vulcanization. Additional mixing stages,sometimes called remills, can be employed between the masterbatch mixingstage and the final mixing stage.

Preparation of Tire

The vulcanizable compositions can be processed into tire componentsaccording to ordinary tire manufacturing techniques including standardrubber shaping, molding and curing techniques. Typically, vulcanizationis effected by heating the vulcanizable composition in a mold; e.g., itmay be heated to about 140° C. to about 180° C. Cured or crosslinkedrubber compositions may be referred to as vulcanizates, which generallycontain three-dimensional polymeric networks that are thermoset. Theother ingredients, such as fillers and processing aids, may be evenlydispersed throughout the crosslinked network. Pneumatic tires can bemade as discussed in U.S. Pat. Nos. 5,866,171, 5,876,527, 5,931,211, and5,971,046, which are incorporated herein by reference.

Vulcanizate Characteristics

As indicated above, the vulcanizable compositions of the presentinvention can be cured to prepare various tire components. These tirecomponents include, without limitation, tire treads, tire sidewalls,belt skims, innerliners, and bead apex.

According to aspects of the present invention, the tire components,which may also be referred to as vulcanizates, are characterized byadvantageous cure characteristics while including relatively low levelsof metal activator such as zinc species.

In one or more embodiments, the vulcanizates are characterized byincluding less than 2 pbw, in other embodiments less than 1 phr, and inother embodiments less than 0.7 pbw zinc per 100 pbw rubber.

In one or more embodiments, the tire component is a tire tread. Whileonly including the limited levels of metal activator, such as zincspecies, as outlined in this specification, the treads nonetheless arecharacterized by a 300% modulus of greater than 3 MPa, in otherembodiments greater than 5 MPa, and in other embodiments greater than 7MPa, as determined by ASTM D-412 at room temperature.

In order to demonstrate the practice of the present invention, severalvulcanizable compositions were in the following experiments. Thevulcanizable compositions were prepared by using the ingredients andmixing order provided in the Tables below. All amounts are presented inparts by weight per 100 parts by weight rubber unless otherwise stated.Generally speaking, the amount and location of zinc oxide and eutecticsolvent were varied throughout the experiments. The following Tablesalso provide the results of some analytical testing that was performedon the compositions and/or vulcanizates prepared therefrom.

Formation of Eutectic Solvent I

A eutectic composition of choline chloride and urea was prepared bymixing one mole of choline chloride with two moles of urea at 100° C. toform a eutectic solvent, which was believed to be a deep eutecticsolvent, which may be referred to as DES-I. The DES-I was allowed tocool to room temperature under standard conditions.

Experiment I

In a first set of experiments, vulcanizable compositions were preparedusing the rubber formulation and mixing order provided in Table I. Thisrubber formulation was indicative of a rubber formulation that is usefulin the manufacture of tire treads. As shown in Table I, the mixprocedure was a three-step mix procedure including a masterbatch mixstep, a “remill mix step,” and a final mix step. The various mixingsteps were performed within a Banbury mixer. During preparation of themasterbatch, the mixer was operated at 75 rpm and a peak compositionaltemperature of 160° C. was attained. At that point in time, thecomposition was dropped from the mixer and allowed to cool to belowabout 85° C. At this point in time, the composition was thenreintroduced to the mixer along with the ingredients identified for the“remill stage,” and mixing was continued at 75 rpm and a peakcompositional temperature of about 160° C. was achieved. The compositionwas again dropped from the mixer and allowed to cool to below about 50°C. Then, the composition was again reintroduced to the mixer along withthe ingredients identified for the “final mix stage.” Included amongthese ingredients was the DES-I and zinc oxide, which were introducedseparately and individually, as provided in Table II. Mixing wascontinued at 40 rpm at with a peak compositional temperature of about100° C. The composition was then dropped from the mixer and samples wereobtained from the composition for purposes of the analytical testing.The results of the analytical testing are provided in Table II.

TABLE I Ingredient phr Master SBR 70 BR 30 Carbon Black (N134) 25 Silica50 Paraffinic oil 10 Wax 2 Stearic acid 2 6PPD (AO) 1 Remill Silica 10Silane 6 Final Sulfur 1.7 DPG 0.5 CBS 1.5 ZnO Variable DES-I Variable

Rheometer measurements were taken using an MDR 2000 operating attemperatures as specified in the Tables. The tensile mechanicalproperties (Max Stress, Modulus, Elongation, and Toughness) of thevulcanizates were measured by using the standard procedure described inASTM-D412. The dynamic rheological properties (e.g. tan δ) of thevulcanizates were obtained from temperature-sweep studies, which wereconducted over the range from about −80° C. to about 80° C. and 10 Hz.

TABLE II Samples: C1 C2 T1 T2 Variable ZnO 2.5 0.5 0.5 0.5 DES 0 0 0.0250.05 MDR @ 171° C. MH-ML(dNm) 21.2 19.2 19.3 19.4 T2S (min) 1.05 1.151.17 1.16 T50 (min) 3.73 2.44 2.36 2.47 T90 (min) 11.3 12.08 10.1 11.3Tensile @ 23° C. Max Stress (MPa) 13.7 12.5 15.1 12.4 50% Modulus (MPa)2.83 3.16 3.06 3.05 100% Modulus (MPa) 4.87 5.57 5.22 5.25 MaxElongation (%) 266 218.6 279 236 Toughness (MPa) 18.7 14.5 21.8 16.6Rheological data Tanδ@0° C. 0.245 0.245 0.255 0.253 Tanδ@60° C. 0.2090.213 0.215 0.212

The data in Table II shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Experiment II

In a second experiment, DES-I prepared using the same proceduredescribed above introduced to vulcanizable compositions of matterprepared using a two-stage mix procedure was used. The ingredients usedand the mixing order are provided in Table III. This rubber formulationis indicative of a rubber formulation that is useful in the manufactureof tire sidewall.

As with the previous experiment, the mix procedure was performed withina Banbury mixer. During preparation of the masterbatch, the mixer wasoperated at 75 rpm and the peak temperature of 160° C. was attained. Atthat point in time, the composition was dropped from the mixer andallowed to cool to below about 85° C. Then, the composition wasreintroduced to the mixer along with the ingredients identified for the“final mix stage,” which included DES-I and zinc oxide in amounts asprovided in Table IV. Mixing was continued at 40 rpm at a peakcompositional temperature of about 100° C.

TABLE III Ingredient Phr Master NR 40 BR 60 Carbon Black (N550) 45Paraffinic oil 6 Wax 1 Stearic acid 2 6PPD (AO) 2.5 TMQ 1.5 Resin 2Final Sulfur 1 CBS 1.2 ZnO Variable DES-I Variable

As with the previous experiments, the samples were subjected toanalytical testing and the results of the tests are set forth in TableIV.

TABLE IV Samples: C3 C4 T3 T4 Variable ZnO 3 1 1 1 DES 0 0 0.05 0.1 MDR@ 145° C. MH-ML(dNm) 12.7 11.8 12.0 12.0 T2S (min) 8.80 8.43 6.54 6.53T50 (min) 10.3 9.91 7.61 7.58 T90 (min) 15.2 14.6 11.2 11.1 Tensile @23° C. Max Stress (MPa) 17.7 19.8 18.6 17.9 50% Modulus (MPa) 1.37 1.351.38 1.40 100% Modulus (MPa) 2.44 2.40 2.48 2.51 300% Modulus (MPa) 10.110.1 10.3 10.4 Max Elongation (%) 487 488 503 479 Toughness (MPa) 49.742.4 45.9 41.8 Rheological data Tanδ@60° C. 0.098 0.089 0.087 0.090

The data in Table IV shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Experiment III

In a third experiment, DES-I, which was prepared using the sameprocedures set forth above, was introduced to a vulcanizable compositionof matter that is indicative of a rubber formulation that is useful inthe manufacture of tire inner liner. The mixing conditions were the sameas provided above for Experiment II. The ingredients used and the mixingorder are provided in Table V.

TABLE V Ingredient phr Master BIIR 100 Carbon Black (N660) 50 Paraffinicoil 8 Resin 7 Stearic acid 2 Final Sulfur 0.5 MBTS 1.5 ZnO Variable DESVariable

As with the previous experiments, the samples were subjected toanalytical testing and the results of the tests are set forth in TableVI.

TABLE VI Samples: C5 C6 T5 T6 Variable ZnO 3 1 1 1 DES 0 0 0.05 0.1 MDR@ 160° C. MH-ML (dNm) 2.50 2.51 2.38 2.37 T2S (min) 5.15 5.54 5.28 5.28T50 (min) 3.15 3.73 3.67 3.62 T90 (min) 9.49 9.01 6.04 6.06 Tensile @23° C. Max Stress (MPa) 8.70 8.60 8.60 8.70 50% Modulus (MPa) 0.8420.767 0.755 0.786 100% Modulus (MPa) 1.34 1.22 1.20 1.29 300% Modulus(MPa) 4.41 4.16 4.05 4.31 Max Elongation (%) 601 593 577 574 Toughness(MPa) 30.6 27.7 27.9 28.9 Rheological data Tanδ@60° C. 0.230 0.183 0.2080.182 Air Permeability Rate (cc · mm/[m²/day]) 17.7 20.2 17.2 19.8

In addition to MDR, mechanical, and rheological properties, thevulcanizates were analyzed for air permeability pursuant to ASTM D-3985.The data in Table VI shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Experiment IV

In a fourth experiment, DES-I, which was prepared using the sameprocedures set forth above, was introduced to a vulcanizable compositionof matter that is indicative of a rubber formulation that is useful inthe manufacture of tire belt skim. The mixing conditions were the sameas provided above for Experiment II. The ingredients used and the mixingorder are provided in Table VII.

TABLE VII Ingredient Phr Master NR 100 Carbon black (N326) 48 Paraffinicoil 2.5 Resin 5 Silica 12 6PPD 2.5 Stearic acid 1.6 FinalHexamethoxymethylmelamine 1.6 Insoluble sulfur 5 DCBS 1.5 ZnO VariableDES Variable

As with the previous experiments, the samples were subjected toanalytical testing and the results of the tests are set forth in TableVIII.

TABLE VIII Samples: C7 C8 T7 T8 Variable ZnO 8 4 4 4 DES 0 0 0.2 0.4 MDR@ 145° C. MH-ML (dNm) 18.7 18.3 19.4 19.8 T2S (min) 4.81 4.75 4.18 3.91T50 (min) 11.3 10.9 10.5 10.5 T90 (min) 25.0 24.4 28.4 28.3 Tensile @23° C. Max Stress (MPa) 24.0 25.5 24.8 23.8 50% Modulus (MPa) 2.39 2.412.39 2.65 100% Modulus (MPa) 4.75 4.82 4.77 5.25 300% Modulus (MPa) 18.318.3 18.8 19.2 Max Elongation (%) 391 413 392 371 Toughness (MPa) 46.151.9 47.1 43.8 Rheological data Tanδ@60° C. 0.167 0.162 0.178 0.175

The data in Table VIII shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Experiment V

In a fifth experiment, DES-I, which was prepared using the sameprocedures set forth above, was introduced to a vulcanizable compositionof matter that is indicative of a rubber formulation that is useful inthe manufacture of tire tread. The mixing conditions were the same asprovided above for Experiment II except that DES-I was introduced withthe masterbatch ingredients as shown in Table IX, which lists theingredients used and the mixing order. As with the previous experiments,the samples were subjected to analytical testing and the results of thetests are also set forth in Table IX.

TABLE IX Samples: C9 C10 T9 C11 C12 T10 T11 C13 C14 T12 Master NR 70 7070 50 50 50 50 100 100 100 BR 30 30 30 30 30 30 30 — — — SBR — — — 20 2020 20 — — — Carbon black (N134) 48 48 48 48 48 48 48 48 48 48 Resin 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Wax 1 1 1 1 1 1 1 1 1 1 Stearic acid2 2 2 2 2 2 2 2 2 2 6PPD (AO) 1 1 1 1 1 1 1 1 1 1 ZnO 3.5 1.75 1.75 3.51.75 1.75 0.70 3.5 1.75 1.75 DES 0 0 0.088 0 0 0.088 0.035 0 0 0.088Final TMQ 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Sulfur 1 1 1 1 1 1 1 11 1 CBS 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 MDR @ 145° C. MH-ML(dNm) 14.6 13.9 14.1 14.8 13.8 14.4 16.4 13.8 13.9 12.9 T2S (min) 7.677.21 7.09 9.58 9.34 8.18 7.33 7.51 7.25 7.48 T50 (min) 9.25 8.49 8.3211.4 11.1 9.80 8.42 8.97 8.53 8.89 T90 (min) 13.59 11.86 11.64 16.2 15.913.4 10.6 13.0 12.6 12.9 Tensile @ 23° C. Max Stress (MPa) 28.3 27.228.7 27.3 27.5 26.5 26.4 31.3 29.7 30.5 50% Modulus (MPa) 1.72 1.71 1.711.81 1.84 1.68 1.68 1.75 1.70 1.68 100% Modulus (MPa) 3.23 3.17 3.183.21 3.34 2.86 2.92 3.53 3.44 3.34 300% Modulus (MPa) 15.1 14.8 15.114.4 15.4 13.0 13.4 17.2 17.1 16.4 Max Elongation (%) 521 501 520 511484 528 526 513 484 546 Toughness (MPa) 70.5 64.6 70.8 65.7 62.1 65.065.5 77.7 67.9 82.9 Rheological data Tanδ@0° C. 0.196 0.220 0.209 0.2420.243 0.245 0.229 0.239 0.238 0.235 Tanδ@60° C. 0.174 0.186 0.181 0.1900.190 0.198 0.192 0.186 0.188 0.186

The data in Table IX shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Formation of Eutectic Solvent II

A eutectic composition of choline chloride and malonic acid was preparedby mixing one mole of choline chloride with one mole of malonic acid at100° C. to form a eutectic solvent, which was believed to be a deepeutectic solvent, which may be referred to as DES-II. The DES-II wasallowed to cool to room temperature under standard conditions.

Experiment VI

In a sixth experiment, DES-I, which was prepared using the sameprocedures set forth above, and DES-II, which was prepared above, wereintroduced to a vulcanizable composition of matter as provided in TableX. The mixing conditions were the same as provided above for ExperimentII, which lists the ingredients used and the mixing order.

TABLE X Ingredient phr Master SBR 100 Final Stearic acid 2 Sulfur 1.3CBS 1.7 ZnO Variable DES (urea) Variable DES (malonic acid) Variable

As with the previous experiments, the samples were subjected toanalytical testing and the results of the tests are also set forth inTable XI.

TABLE XI C15 T13 T14 T15 T16 Variable ZnO 2.0 0.5 0.5 0.5 0.5 DES-I 00.025 0.05 0 0 DES-II 0 0 0 0.025 0.05 MDR @ 171° C. MH-ML (dNm) 8.368.07 8.44 8.16 8.34 T2S (min) 9.88 8.56 7.71 8.46 7.38 T50 (min) 10.69.12 8.22 8.96 7.81 T90 (min) 13.9 11.6 10.6 11.5 10.1 Tensile @ 23° C.Max Stress (MPa) 1.70 1.90 1.60 1.70 1.80 50% Modulus (MPa) 0.873 0.8560.875 0.860 0.886 100% Modulus (MPa) 1.25 1.23 1.25 1.22 1.28 MaxElongation (%) 159 185 149 160 169

The data in Table VIII shows that the loading of ZnO can be appreciablyreduced in the presence of the eutectic solvent.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1-93. (canceled)
 94. A method for preparing a vulcanizable compositionof matter, the method comprising: combining a vulcanizable rubber, acurative, a metal compound, and a eutectic composition.
 95. The methodof claim 94, where said metal compound is zinc oxide.
 96. The method forpreparing a vulcanizable composition of matter of claim 95, where saidvulcanizable composition includes less than 2 parts by weight zinc oxideper 100 parts by weight rubber.
 97. The method for preparing avulcanizable composition of matter of claim 94, where the eutecticcomposition is formed by combining choline chloride and urea.
 98. Themethod for preparing a vulcanizable composition of matter of claim 94,where the vulcanizable composition includes from about 0.005 to about 3parts by weight of the eutectic composition per 100 parts by weightrubber.
 99. The method for preparing a vulcanizable composition ofmatter of claim 94, where eutectic composition is defined by the formulaCat+X−zY, where Cat+ is a cation, X− is a counter anion (e.g. LewisBase), and z refers to the number of Y molecules that interact with thecounter anion (e.g. Lewis or Bronsted Acid).
 100. The method forpreparing a vulcanizable composition of matter of claim 99, where Cat+is an ammonium, phosphonium, or sulfonium cation and X⁻ is a halide ion.101. The method for preparing a vulcanizable composition of matter ofclaim 94, where the eutectic composition is formed by combining anammonium compound with a metal halide, a metal halide hydrate, or ahydrogen bond donor, where the ammonium compound ammonium compounds, maybe defined by the formula II:(R₁)(R₂)(R₃)(R₄)—N⁺-ϕ⁻ where each R₁, R₂, R₃, and R₄ is individuallyhydrogen or a monovalent organic group, or, in the alternative, two ofR₁, R₂, R₃, and R₄ join to form a divalent organic group, and ϕ⁻ is acounter anion; and where the hydrogen bond donor is selected from thegroup consisting of amines, amides, carboxylic acids, and alcohols. 102.A vulcanizate prepared from the method for preparing a vulcanizablecomposition of matter of claim 94, where said vulcanizate is formed by astep of heating the vulcanizable composition to thereby effectvulcanization.
 103. A rubber vulcanizate comprising: a vulcanized rubbernetwork including a metal compound dispersed throughout the rubbernetwork, where said metal compound is zinc oxide and said vulcanizedrubber including less than 2 parts by weight zinc oxide per 100 parts byweight rubber.
 104. The rubber vulcanizate of claim 103 where the rubbervulcanizate is a tire tread, and where rubber vulcanizate ischaracterized by a 300% modulus that is greater than 3 MPa.
 105. Therubber vulcanizate of any of claim 103, where said vulcanized rubberincludes less than 1 parts by weight zinc oxide per 100 parts by weightrubber.
 106. The rubber vulcanizate of any of claim 103, where therubber vulcanizate includes a eutectic composition or the residue of aeutectic composition.
 107. The rubber vulcanizate of claim 103, wherethe eutectic composition is defined by the formula Cat+X−zY, where Cat+is a cation, X− is a counter anion (e.g. Lewis Base), and z refers tothe number of Y molecules that interact with the counter anion (e.g.Lewis or Bronsted Acid).
 108. The rubber vulcanizate of claim 107, whereCat+ is an ammonium, phosphonium, or sulfonium cation and X⁻ is a halideion.
 109. The rubber vulcanizate of claim 103, where the eutecticcomposition is selected from the group consisting of Type I, Type II,Type III, and Type IV eutectic compositions.
 110. The rubber vulcanizateof claim 103, where the eutectic composition is formed by combining anammonium compound with a metal halide, a metal halide hydrate, or ahydrogen bond donor.
 111. The rubber vulcanizate of claim 103, where theammonium compound ammonium compounds, may be defined by the formula II:(R₁)(R₂)(R₃)(R₄)—N⁺-ϕ⁻ where each R₁, R₂, R₃, and R₄ is individuallyhydrogen or a monovalent organic group, or, in the alternative, two ofR₁, R₂, R₃, and R₄ join to form a divalent organic group, and ϕ⁻ is acounter anion.
 112. The rubber vulcanizate of claim 110, where the metalhalide is selected from the group consisting of aluminum chloride,aluminum bromide, aluminum iodide, zinc chloride, zinc bromide, zinciodide, tin chloride, tin bromide, tin iodide, iron chloride, ironbromide, iron iodide, and combinations thereof.
 113. The rubbervulcanizate of claim 103, where the zinc oxide is dissolved in theeutectic solvent.